Cool. I had a feeling I found it. You are right! The end looks like a nail head with a spark-plug-like base. I found a pair of green wires attached to the valve cover. One goes to some kind of electromagnetic plunger attached near the throttle. The other ends in a jagged stripped end with no connector! I put a voltmeter on the bare wire and got nothing with the key "on" and the engine running. I suspect this wire will show +12v when I turn on the A/C. Currently, the A/C compressor is disconnected because of a leak, and the connector is missing the +12v lead. I may be wrong - this has happened many times in my life.
